Assistance with under-gassed ar15 build?

[ma96782]

One vs the other.

Maybe......it's the weight or the actual size of the BCG or the finish adding friction or even the locking itself? Anyway......you could always just start another build. Isn't that how most of these endless projects begin? LOL.



Aloha, Mark

 

[arrowshooter]

When you first put it together did you cycle the bolt 100 - 200 times with a light amount of oil?

 

[P7M13]

When you first put it together did you cycle the bolt 100 - 200 times with a light amount of oil?

I'm guilty of *never* having done that....

 

[titsonritz]

Yes, I previously made sure the rings were staggered. two of them weren't the first time I tested it, but the malfunctions still occurred while they were staggered.

There is no need to stagger the rings, that is a BS myth courtesy of Uncle Sam. That channel in the carrier reduces in diameter which compresses the rings together during it's path of travel.

ETA: Mike with SOLGW explains and proves it...

 

[titsonritz]

@Cerberus Group didn't you say you've gauged several Aero BCGs and they were all over the place dimensionally?

 

[Cerberus Group]

@Cerberus Group didn't you say you've gauged several Aero BCGs and they were all over the place dimensionally?

Aero is dead-nuts on, with all I've tested...Radian and Ballistic Advantage don't gauge out well.

 

[kmk1012]

Not to derail this thread but how long is a buffer? The rifle I'm having issues with locking back on empty mag has a buffer that's six inches or longer. I thought most buffers were shorter than that. I realigned the gas block using the spaghetti trick and now it will cycle and eject, just not lock on empty mag. Should I move to a lighter buffer? I've tried multiple ammo types, most were 556, some were warm 223 loads too. If I should open a new thread let me know and I apologize.

 

[Cerberus Group]

Not to derail this thread but how long is a buffer? The rifle I'm having issues with locking back on empty mag has a buffer that's six inches or longer. I thought most buffers were shorter than that. I realigned the gas block using the spaghetti trick and now it will cycle and eject, just not lock on empty mag. Should I move to a lighter buffer? I've tried multiple ammo types, most were 556, some were warm 223 loads too. If I should open a new thread let me know and I apologize.

A carbine buffer is roughly 3.25"

 

[kmk1012]

A carbine buffer is roughly 3.25"

That's what I was thinking, remembering. I believe I have a true rifle buffer that's a little heavy for this setup. I may swap another one tomorrow eve and function test. This is actually my son's rifle that I decked out with wood furniture and a nice scope I'm trying to get ready for a eastern Oregon trip in two weeks.

 

[titsonritz]

Not to derail this thread but how long is a buffer? The rifle I'm having issues with locking back on empty mag has a buffer that's six inches or longer. I thought most buffers were shorter than that. I realigned the gas block using the spaghetti trick and now it will cycle and eject, just not lock on empty mag. Should I move to a lighter buffer? I've tried multiple ammo types, most were 556, some were warm 223 loads too. If I should open a new thread let me know and I apologize.

Carbine buffers are ~3.25" for use in carbine RE w/ a carbine action spring w/ the following weights:
Carbine = 2.9oz
H = 3.8oz
H2 = 4.5-4.7oz
H3 = 5.3-5.5oz
H6 = 5.2oz (intended for Carbine RE w/ 20" rifle barrel)

Vltor A5 buffers are ~4" for use in an A5 RE w/ a rifle action spring w/ the following weights:
H0 = 3.8oz
H1 = 4.56oz
H2 = 5.33oz
H3 = 6.08oz
H4 = 6.83oz

Rifle buffers are ~6" for use in rifle RE w/ a rifle action spring and weigh 5.1-5.3oz

A carbine spring should measure between 10 1/16" - 11 1/4"
A rifle spring should measure between 11 3/4" - 13 1/2"
If spring shorter than minimum length it is worn out and should be replaced

 

[Cerberus Group]

That's what I was thinking, remembering. I believe I have a true rifle buffer that's a little heavy for this setup. I may swap another one tomorrow eve and function test. This is actually my son's rifle that I decked out with wood furniture and a nice scope I'm trying to get ready for a eastern Oregon trip in two weeks.

A true rifle buffer in a carbine tube?

 

[titsonritz]

A true rifle buffer in a carbine tube?

Yeah, that's not going to work. Shouldn't be able to lock back even manually let alone being fired.

 

[kmk1012]

A true rifle buffer in a carbine tube?

No sir, a rifle length buffer with a rifle length tube and spring. Gas block was slightly misaligned and corrected that tonight, will reliably fire and eject now, just not enough oomph to lock open on empty mag. That's why I was hoping to do a simple buffer swap to help out and was confused after seeing a six plus inch buffer when I'm used to much shorter.

 

[titsonritz]

@kmk1012

If you're trying to fit this...



into this...



that ain't going to work.

 

[titsonritz]

No sir, a rifle length buffer with a rifle length tube and spring. Gas block was slightly misaligned and corrected that tonight, will reliably fire and eject now, just not enough oomph to lock open on empty mag. That's why I was hoping to do a simple buffer swap to help out and was confused after seeing a six plus inch buffer when I'm used to much shorter.

Never mind on my last post. Is the gun well lubed? If not lube it wet. What ammo are you using? I always use full power NATO ammo when doing diagnostics.

 

[kmk1012]

@kmk1012

If you're trying to fit this...

View attachment 1402411

into this...

View attachment 1402412

that ain't going to work.

Nope, came as a kit-rifle length for the fixed stock.

 

[kmk1012]

Never mind on my last post. Is the gun well lubed? If not lube it wet. What ammo are you using? I always use full power NATO ammo when doing diagnostics.

Yes, have tried full power 556 ammo but want to use some "warm", almost hot reloaded ballistic tip vmax loads that work in other AR's with identical setups for sage rat duty. It at least cycles rounds now and I'm just trying to get it to lock on an empty mag. I feel that a slightly lighter weight buffer will allow the BCG to move ever so slightly back further and lock open if that makes sense.

 

[DirectDrive]

No sir, a rifle length buffer with a rifle length tube and spring. Gas block was slightly misaligned and corrected that tonight, will reliably fire and eject now, just not enough oomph to lock open on empty mag. That's why I was hoping to do a simple buffer swap to help out and was confused after seeing a six plus inch buffer when I'm used to much shorter.

Can you lock back the BCG manually ?

 

[kmk1012]

Can you lock back the BCG manually ?

Yes, it just seems like the bcg doesn't travel far enough back by just a fraction of an inch. This is while firing, I can manually pull the charging handle and manipulate the bolt release and lock it.

 

[DirectDrive]

Yes, it just seems like the bcg doesn't travel far enough back by just a fraction of an inch. This is while firing, I can manually pull the charging handle and manipulate the bolt release and lock it.

So you have to kind of force it to lock back ?